Dear Woodbutcher,Turn the setting to Vacation on your water heater. It will keep the water from freezing if the temp drops. If it gets real cold where you live, pour automotive anti-freeze into your toilets and sink traps. This will stop the traps from exploding during a freeze. Use compressed air to blow out your water lines. If you're worried about the glycol, there won't be enough getting into the ground to worry about.Len